This invention relates to a radiation detection device.
By "radiation," in particular an x-ray radiation or a gamma radiation or even a radiation consisting of high-energy electrons is meant.
The invention finds applications in many fields, in particular in physics (x-ray crystallography . . . ), in the medical field (radiography, tomography, angiography . . . ), in the industrial field (detection of defects, welding inspection . . . ) and in the field of security (luggage inspection . . . ).
Various radiation detection devices are already known.
Thus, a photographic plate combined with an intensifing screen has constituted for a long time the only means to achieve the acquisition and the display of x images. Moreover, this technique is still now in use but is gradually being replaced by systems achieving the acquisition of an x image in digital form to be able to display it in real time, without requiring the stage of development and of fixing that the traditional photographic systems require.
Several systems making possible the acquisition of an x image in digital form are already known but present drawbacks:
The wire chambers, for example, marketed by the Schlumberger Company, have a detection effectiveness which is limited to about 25%.
Such an effectiveness is obtained, moreover, only with a fairly large chamber. The spatial resolution of these chambers is not very good (on the order of several millimeters). Moreover, these chambers are filled with gas (argon or xenon, for example) whose gradual pollution is troublesome, the chambers requiring a recycling system which is bulky.
The systems, for example marketed by the Thomson Company, comprising photodiodes which are combined in bars with a pitch of 1 or 0.5 mm and which are preceded by a scintillation counter consisting of a layer of about 0.3 mm of Gd.sub.2 O.sub.2 S, have a low detection effectiveness above 100 keV given the slight thickness of the scintillation counter. This thickness cannot be increased, however, without running the risk of deteriorating the spatial resolution. Moreover, this scintillation counter presents a significant reduction of visible photons.
The brilliance amplifiers, for example marketed by the Philips and Thomson companies, constitute bidimensional sensors, which can be advantageous in some case, because no outer scanning system is necessary. However, these brilliance amplifiers present several drawbacks, namely a great sensitivity to the x rays diffused by an object to be analyzed and limited dynamics and, finally, the necessity of a compromise between the resolution and the stopping power of these brilliance amplifiers.
This invention relates to a radiation detection device which, contrary to known devices mentioned above, exhibits both a great detection effectiveness and a good spatial resolution.